Can a tax planner be both ethical and aggressive? When a client wants help with a transaction in which the lawyer thinks the tax benefits will probably not be sustained on the merits if challenged, what is the ethical response? How low should the tax adviser go?

The rules of ethics and standards of tax practice generally do not answer these questions. And there is a dearth of guidance about what it means to behave ethically when making discretionary decisions about when and how to provide advice for aggressive tax planning. This article fills that gap and argues that a lawyer seeking to pursue a career as an ethical tax planner should identify and implement her philosophy of lawyering to help her make these difficult discretionary decisions in a principled way. Using, as an example, a U.S. multinational corporation that wants to invert and engage in other potentially aggressive cross-border tax reduction strategies that Congress and the Treasury have repeatedly tried to curtail, this article demonstrates that employing a philosophy of lawyering empowers a tax planner determine how (and whether) to assist this client. Ultimately, this article helps a tax planner operationalize, on an individual basis and in a way that aligns with her values, both the general and tax-specific rules of professional conduct so that she can answer the questions posed above.